1. Field of the Invention
The present invention relates generally to air conditioner systems for automotive vehicles, and more particularly to an automobile air conditioner system including a variable displacement compressor.
2. Prior Art
There have been proposed various automobile air conditioner systems of the type described. One such proposal is disclosed in Japanese Patent Laid-open Publication No. 60-162087. The disclosed system includes a solenoid valve for relieving the pressure in a crank room in a compressor toward the intake side of the compressor. The solenoid valve is controlled to open and close at a duty ratio according to the thermal loads in a vehicle compartment to be cooled, thereby adjustably controlling the displacement of the compressor.
The disclosed system thus constructed is disadvantageous however in that an electric circuit incorporated in the system is complicated in construction due to the necessity of a duty pulse generator and, for stable control, a feedback control based on continuous detection of, for example, the temperature of an evaporator.